498 ANNUAL REPORT OF THE Off. Doc. 



Barnyard manure, already mentioned above, would come under 

 this class of slow acting fertilizers for the most part, although some 

 of its nitrogen may l)e in the ammoniacal form and very quickly avail- 

 able. 



There remains two products which should be mentioned now: 



Calcium cijanaiiiidc or liiiie-nitrogen, a substance made in Europe 

 by heating in an electric furnace a mixture of coke or charcoal and 

 lime over which is passed a stream of nitrogen. The nitrogen is 

 obtained with but little trouble from the air. The final product is 

 a compound containing 17-20 per cent, nitrogen which decomposes on 

 treatment with water to form ammonia. This of course is what 

 happens when lime-nitrogen is added to the soil; and the ammonia 

 can very quickly be changed to nitrates for plant use. It is a fer- 

 tilizer of the second class, can be made cheaply, and is almost as 

 good a fertilizer as sodium nitrate. 



Basic calciuin nitrate is a fertilizer now on the European markets 

 to some extent, as cheap as, or cheaper than sodium nitrate and 

 exactly as good, containing about the same amount of nitrogen, 18-15 

 per cent. It is made in Norway by passing air through a furnace con- 

 taining an immense disc-shaped arc, some five or six feet in diameter, 

 produced by a very powerful electric current between water cooled 

 copper electrodes. The disc-shape of the arc is obtained by an im- 

 mense electro magnet which pulls the ordinary arc out of shape. The 

 action of this intense heat on the nitrogen and oxygen of the air 

 causes them to unite to form oxides of nitrogen. These oxides of 

 nitrogen are passed up through granite towers full of crushed quartz 

 down through which trickles water. Nitric acid is formed. This 

 nitric acid can be concentrated and sold as such, or it can be neu- 

 tralized by lime and the basic calcium nitrate formed. 



We have here a process which makes nitric acid for use in com- 

 merce, and nitrate for use in agriculture. Air is the source of nitro- 

 gen for useful articles and for necessary crops. We can be indepen- 

 dent of the naturally occurring instincts of soda; its disappearance 

 need not cause any anxiety. And more than this the farmer has in 

 the bacteria on his clover and alfalfa roots an agency for utilizing 

 atmospheric nitrogen which is cheap, efficient and reliable. 



The nitrogen problem is solved; we have bound it and become 

 its master; we have brought its inexhaustible sources into service. 



REPOET OF THE MICROSCOPIST AND HYGIENIST 



By PROF. JAMES W. KELLOGG 



At our meeting last year an attempt was made to illustrate how 

 the microscope has been of great aid to the scientist in the investiga-. 

 tion of food adulterations, and the detection of the source of dis- 

 ease, and to bring before you the importance and need of a law which, 

 would regulate and cri«trol the, e^nitary conditions of the communi-- 

 til?s in which we live. 



